A typical high power, radio frequency (RF) semiconductor device may include one or more input leads, one or more output leads, one or more transistors, bondwires coupling the input lead(s) to the transistor(s), and bondwires coupling the transistor(s) to the output lead(s). The bondwires have significant inductive reactance at high frequencies, and such inductances are factored into the design of input and output impedance matching circuits for a device. In some cases, input and output impedance matching circuits may be contained within the same package that contains the device's transistor(s). More specifically, an in-package, input impedance matching circuit may be coupled between a device's input lead and a control terminal (e.g., the gate) of a transistor, and an in-package, output impedance matching circuit may be coupled between a current conducting terminal (e.g., the drain) of a transistor and a device's output lead.
Packaged RF semiconductor devices are available that have decent performance when used in relatively narrow-band applications with relatively low instantaneous signal bandwidth (ISBW) (e.g., ISBW of 150 megahertz (MHz) or less). However, increased ISBW (e.g., ISBW of 200 MHz or more) is becoming a major requirement for RF communication amplifiers (e.g., RF communication infrastructure amplifiers). This requirement stems from the fact that larger information download rates per second are becoming a significant enablement feature. Thus, trends in the RF communication industry include development of packaged RF semiconductor devices with increasingly wideband operation and relatively high ISBW.
Designing RF amplifier devices with high ISBW is challenging. For example, the ISBW of a device may be directly affected by the low frequency resonance (LFR) caused by interaction between the device's bias feeds and output circuits that are electrically connected between a device's transistor(s) and its output lead(s). More particularly, inductances of bondwires that interconnect various output circuit components may limit the LFR of the device.